The invention may find applications in all fields where it is required or at least desirable that an error-correcting code be available. Thus, the invention may be applied for example, to:                protection against errors due to noises and interferences inherent in physical transmission channels (conventional error correction coding and space-time codes for multi-antenna systems);        compression of signals from information sources: images, sounds, signals, and data;        protection against errors for storage of data mass memories, such as computer disks or microprocessors.        
A large number of coding techniques for correcting errors are already known. First studies on the subject go back to the 1940s. It was at that time that Shannon founded the theory of information which is still used presently. A large number of coding families were proposed later.
Convolutive codes are thus known (which may notably apply trellis coding, according to the Viterbi algorithm), or even the coding scheme currently designated as “turbo-code”, proposed in 1993 by C. Berrou and A. Glavieux, for example in the article “Near Shannon Limit Error-Correcting Coding and Decoding: Turbo-codes” (proofreadings of the ICC'93, May 1993, 1064-1070).
This technique was the subject of many studies and improvements.
The family of codes known as LDPC codes is also known.
Turbo-codes and LDPC codes and more generally all concatenated codes provide performances in terms of correction which are remarkable for large block sizes and notably for blocks of at least a few thousands or tens of thousands of information bits.
Unfortunately, the handling of such blocks of information bits represents great computing complexity upon decoding, which practically proves to be only compatible with high computing power microprocessors which accordingly prove to be relatively costly.
Moreover, these structures on the other hand are not very effective in correcting errors for blocks with small sizes, of the order of one hundred or one thousand bits, for example.
However, there is a very strong demand for small packet communications presently in the field of digital communications, which assumes application of codes with small lengths.
The aim of the invention is notably to provide a solution to this need and to overcome the drawbacks of prior techniques.
More specifically, it is an aim of the invention to provide an error correction coding technique, notably of the “turbo-code” type, for reducing the complexity of decoding.
In other words, the aim of the invention is to provide such a coding technique for producing a simplified decoder and therefore at a reduced cost, without naturally degrading the quality of the error correction.
It is another aim of the invention to provide such a coding technique which is well adapted to error correction for blocks of small sizes.
In other words, another aim of the invention is to provide such a technique providing proper minimum distances in spite of small block sizes.
Still another aim of the invention is to provide such a technique for producing coding and decoding in a simple way, and which accordingly may be easily applied.